I think 3-stage New Glenn could end up with higher payload to TLI than SLS Block 1 if fully expended, with ~25000 kg or slightly more. Lots of uncertainty in that one though, particular whether Blue will want to launch any fully expendable.

How complicated could refueling a FH upper stage be? Docking, slowly spinning to make the fuel go to the bottom of he tanks, pumping? There is a lot of moving around just to dock with the space station. Refueling has to be mastered for going to Mars, why not start with FH upper stage or even a NG upper stage when it comes on line? Or even Vulcan refueling upper stage? At some point refueling is going to have to take place to go to Mars. For SpaceX or for New Glenn for that matter, with reusable first stages, refueling second stages, it still seems it would be cheaper to launch Orion on one of these rockets, refuel, then go to cis-lunar space. No need for SLS at twice the cost.

For that matter, why not just launch a complete FH upper stage fully fueled or a stretched upper stage no payload. Dock Orion to it, then proceed to cis-lunar. No need for refueling. Just separate the booster upper stage, and redock with a new upper stage either sent on a F9 or another FH. Two FH launches are still cheaper than one SLS launch.

So, NASA is supposed to just wait for these proposed launch vehicles to finally appear? Falcon Heavy was supposed to fly in 2013. [...] NASA can't wait for promises when it has the propulsion in hand.

What "propulsion" does NASA have "in hand"? They haven't even figured out how to weld the tanks.[...] So in what way would NASA be "waiting" for FH, but have SLS "in hand"?

NASA has RS-25 and five-segment booster and RL10 and, for Orion, AJ-10. In-hand.

Not so. The RS-25's have no core to ride. The core isn't built, NASA is "waiting on" Boeing to build it. The new RS-25s are a different design that NASA is "waiting on", at a cost of $1.15 billion. The AJ-10 has no service module to ride, NASA is "waiting on" the ESA's contractors. And the RL-10C's have no upper-stage to ride on, NASA is "waiting on" Boeing to build that too, and it isn't expected to be ready until 2021 at the earliest, and we all know that date is garbage. Only the ICPS could reasonably be considered "available".

[Falcon Heavy] The way SpaceX wants to fly it (recovering boosters and first stage)

That's the kind of artificially forced comparison that got us Ares and SLS in the first place. There's no such restriction. Sx are happy to sell expendable versions to anyone who wants to pay.

And the worst-case price is so much less than the actual spending on SLS development, that the comparisons get silly. (Like being able to buy 100 FH launches for the spending projected for SLS/Orion for the first four SLS launches (even ignoring sunk-costs.))

Even if the entire rocket was thrown away it would not match even SLS Block 1

Other than the Orion+SM+LAS stack, there's no module for any mission proposal that requires more than 25 tonnes. Most less. Everything bigger is actually multiple stand-alone modules that could be launched separately.

SLS isn't capable of performing any proposed HSF mission (other than a lunar orbit) without multiple launches and orbital assembly. And SLS isn't capable of multiple launches at a cadence suitable for such missions.

Nor can an SLS-dominated agency work on any hardware necessary for BEO HSF for at least another decade. By which time we'll have had two decades of lost development and production experience of in-space hardware.

Talking about SLS's capacity is therefore meaningless. It's capacity is zero. If you have SLS, you can't fly missions.

Although an obvious long-term goal, refuelling isn't necessary at this stage (no pun intended), for the types of missions proposed by NASA.

DRA 5.0 proposes a modular transfer-stage. LM's being shopping ACES to anyone who stands still long enough. And there's a bunch of other contractors working on new hardware and systems that would be suitable for such a beast.

Since any HSF mission beyond a lunar orbit is beyond the capability of SLS without multiple launches, it seems obvious that a modular transfer-stage is a gating technology for any major NASA mission. But having a modular transfer stage would expand the capacity of any current or future launcher. (Except SLS, because it can't maintain the necessary launch cadence for useful missions.)

F9 B5 Expendable GTO payload is 8300 kg per SpaceX. The upper stage is ~4500 kg and the MVac 348s Isp, so total mass inserted to GEO-1800 is 12800 kg. TLI is 725 m/s beyond GEO-1800, so total mass inserted to TLI would be 10300 kg which corresponds to 5800 kg of payload.

MTLI = ((MGTO+MUS)/e725/3414)-MUS

Using the same logic for FH yields 20650 kg translunar payload from its specified GTO payload of 26,600 kg.

Edit: Attempting this for other launchers is somewhat difficult, as we don't have all that information. For New Glenn, we know the GTO payload is expected to be 10-13 tonnes. Based on my RPA calcs, the BE-4U should have an Isp near 365 seconds. The upper stage mass is harder to estimate, but from published pictures it's volume is 3 to 4 times that of the F9 upper stage; and the thrust of the BE-4U is 3x that of the F9 upper stage. So the stage should be around 3.5 x 4500 = ~15750 kg.

Plugging those into the above equation gives a New Glenn reusable TLI payload between 5275 and 7725 kg. Slightly less than what FH can do with downrange landing, but the extra liftoff thrust, additional 1/2 stage and better match between payload mass and stage mass makes a difference for FH.

Two fully expendable FH launches are cheaper than four months of SLS funding.

Since this isn't published by SpaceX, what are your assumptions for these prices?

SpaceX offers the reusable FH at $90m, with a suggested payload of >8t to GTO. They suggest the equivalent expendable payload is >24t to GTO. So I simply tripled the price. Judging by F9 pricing, that's way, way too high, completely unfair to SpaceX. But as you note, and again looking at the F9 prices, the price for NASA tends to be higher; so triple seems a reasonable fudge. And at these prices, even if I'm out by 50%, it doesn't change the result. Hell, even if I'm out by 400% it doesn't change my point.